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                    程序结构
            
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                    变量
            
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                    类型
            
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                    基础数据类型
            
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                    整型
            
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                    布尔型
            
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                    字符串
            
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                    常量
            
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                    复合数据类型
            
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                    Map
            
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                    结构体
            
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                    JSON
            
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                    文本和HTML模板
            
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                    函数
            
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                    函数声明
            
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                    递归
            
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                    多返回值
            
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                    错误
            
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                    函数值
            
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                    匿名函数
            
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                    可变参数
            
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                    Deferred函数
            
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                    Panic异常
            
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                    Recover捕获异常
            
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                    方法
            
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                    方法声明
            
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                    基于指针对象的方法
            
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                    通过嵌入结构体来扩展类型
            
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                    方法值和方法表达式
            
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                    示例: Bit数组
            
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                    封装
            
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                    接口
            
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                    接口是合约
            
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        <li class="chapter " data-level="1.8.2" data-path="ch7-02.html">
            
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                    接口类型
            
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                    实现接口的条件
            
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        <li class="chapter " data-level="1.8.4" data-path="ch7-04.html">
            
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                    flag.Value接口
            
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                    接口值
            
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                    sort.Interface接口
            
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        <li class="chapter " data-level="1.8.7" data-path="ch7-07.html">
            
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                    http.Handler接口
            
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                    error接口
            
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                    示例: 表达式求值
            
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        <li class="chapter " data-level="1.8.10" data-path="ch7-10.html">
            
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                    类型断言
            
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        <li class="chapter " data-level="1.8.11" data-path="ch7-11.html">
            
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                    基于类型断言识别错误类型
            
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        <li class="chapter " data-level="1.8.12" data-path="ch7-12.html">
            
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                    通过类型断言查询接口
            
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        <li class="chapter active" data-level="1.8.13" data-path="ch7-13.html">
            
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                    类型分支
            
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        <li class="chapter " data-level="1.8.14" data-path="ch7-14.html">
            
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                    示例: 基于标记的XML解码
            
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                    补充几点
            
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        <li class="chapter " data-level="1.9" data-path="../ch8/ch8.html">
            
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                    Goroutines和Channels
            
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                    Goroutines
            
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        <li class="chapter " data-level="1.9.2" data-path="../ch8/ch8-02.html">
            
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                    示例: 并发的Clock服务
            
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        <li class="chapter " data-level="1.9.3" data-path="../ch8/ch8-03.html">
            
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                    示例: 并发的Echo服务
            
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        <li class="chapter " data-level="1.9.4" data-path="../ch8/ch8-04.html">
            
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                    Channels
            
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        <li class="chapter " data-level="1.9.5" data-path="../ch8/ch8-05.html">
            
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                    并发的循环
            
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        <li class="chapter " data-level="1.9.6" data-path="../ch8/ch8-06.html">
            
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                    示例: 并发的Web爬虫
            
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        <li class="chapter " data-level="1.9.7" data-path="../ch8/ch8-07.html">
            
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                    基于select的多路复用
            
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                    示例: 并发的目录遍历
            
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        <li class="chapter " data-level="1.9.9" data-path="../ch8/ch8-09.html">
            
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                    并发的退出
            
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        <li class="chapter " data-level="1.9.10" data-path="../ch8/ch8-10.html">
            
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                    示例: 聊天服务
            
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        <li class="chapter " data-level="1.10" data-path="../ch9/ch9.html">
            
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                    基于共享变量的并发
            
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        <li class="chapter " data-level="1.10.1" data-path="../ch9/ch9-01.html">
            
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                    竞争条件
            
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        <li class="chapter " data-level="1.10.2" data-path="../ch9/ch9-02.html">
            
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                    sync.Mutex互斥锁
            
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        <li class="chapter " data-level="1.10.3" data-path="../ch9/ch9-03.html">
            
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                    sync.RWMutex读写锁
            
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        <li class="chapter " data-level="1.10.4" data-path="../ch9/ch9-04.html">
            
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                    内存同步
            
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        <li class="chapter " data-level="1.10.5" data-path="../ch9/ch9-05.html">
            
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                    sync.Once惰性初始化
            
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        <li class="chapter " data-level="1.10.6" data-path="../ch9/ch9-06.html">
            
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                    竞争条件检测
            
                </a>
            

            
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        <li class="chapter " data-level="1.10.7" data-path="../ch9/ch9-07.html">
            
                <a href="../ch9/ch9-07.html">
            
                    
                    示例: 并发的非阻塞缓存
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.10.8" data-path="../ch9/ch9-08.html">
            
                <a href="../ch9/ch9-08.html">
            
                    
                    Goroutines和线程
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.11" data-path="../ch10/ch10.html">
            
                <a href="../ch10/ch10.html">
            
                    
                    包和工具
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.11.1" data-path="../ch10/ch10-01.html">
            
                <a href="../ch10/ch10-01.html">
            
                    
                    包简介
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.2" data-path="../ch10/ch10-02.html">
            
                <a href="../ch10/ch10-02.html">
            
                    
                    导入路径
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.3" data-path="../ch10/ch10-03.html">
            
                <a href="../ch10/ch10-03.html">
            
                    
                    包声明
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.4" data-path="../ch10/ch10-04.html">
            
                <a href="../ch10/ch10-04.html">
            
                    
                    导入声明
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.5" data-path="../ch10/ch10-05.html">
            
                <a href="../ch10/ch10-05.html">
            
                    
                    包的匿名导入
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.6" data-path="../ch10/ch10-06.html">
            
                <a href="../ch10/ch10-06.html">
            
                    
                    包和命名
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.7" data-path="../ch10/ch10-07.html">
            
                <a href="../ch10/ch10-07.html">
            
                    
                    工具
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.12" data-path="../ch11/ch11.html">
            
                <a href="../ch11/ch11.html">
            
                    
                    测试
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.12.1" data-path="../ch11/ch11-01.html">
            
                <a href="../ch11/ch11-01.html">
            
                    
                    go test
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.2" data-path="../ch11/ch11-02.html">
            
                <a href="../ch11/ch11-02.html">
            
                    
                    测试函数
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.3" data-path="../ch11/ch11-03.html">
            
                <a href="../ch11/ch11-03.html">
            
                    
                    测试覆盖率
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.4" data-path="../ch11/ch11-04.html">
            
                <a href="../ch11/ch11-04.html">
            
                    
                    基准测试
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.5" data-path="../ch11/ch11-05.html">
            
                <a href="../ch11/ch11-05.html">
            
                    
                    剖析
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.6" data-path="../ch11/ch11-06.html">
            
                <a href="../ch11/ch11-06.html">
            
                    
                    示例函数
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.13" data-path="../ch12/ch12.html">
            
                <a href="../ch12/ch12.html">
            
                    
                    反射
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.13.1" data-path="../ch12/ch12-01.html">
            
                <a href="../ch12/ch12-01.html">
            
                    
                    为何需要反射?
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.2" data-path="../ch12/ch12-02.html">
            
                <a href="../ch12/ch12-02.html">
            
                    
                    reflect.Type和reflect.Value
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.3" data-path="../ch12/ch12-03.html">
            
                <a href="../ch12/ch12-03.html">
            
                    
                    Display递归打印
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.4" data-path="../ch12/ch12-04.html">
            
                <a href="../ch12/ch12-04.html">
            
                    
                    示例: 编码S表达式
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.5" data-path="../ch12/ch12-05.html">
            
                <a href="../ch12/ch12-05.html">
            
                    
                    通过reflect.Value修改值
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.6" data-path="../ch12/ch12-06.html">
            
                <a href="../ch12/ch12-06.html">
            
                    
                    示例: 解码S表达式
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.7" data-path="../ch12/ch12-07.html">
            
                <a href="../ch12/ch12-07.html">
            
                    
                    获取结构体字段标签
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.8" data-path="../ch12/ch12-08.html">
            
                <a href="../ch12/ch12-08.html">
            
                    
                    显示一个类型的方法集
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.9" data-path="../ch12/ch12-09.html">
            
                <a href="../ch12/ch12-09.html">
            
                    
                    几点忠告
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.14" data-path="../ch13/ch13.html">
            
                <a href="../ch13/ch13.html">
            
                    
                    底层编程
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.14.1" data-path="../ch13/ch13-01.html">
            
                <a href="../ch13/ch13-01.html">
            
                    
                    unsafe.Sizeof, Alignof 和 Offsetof
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.2" data-path="../ch13/ch13-02.html">
            
                <a href="../ch13/ch13-02.html">
            
                    
                    unsafe.Pointer
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.3" data-path="../ch13/ch13-03.html">
            
                <a href="../ch13/ch13-03.html">
            
                    
                    示例: 深度相等判断
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.4" data-path="../ch13/ch13-04.html">
            
                <a href="../ch13/ch13-04.html">
            
                    
                    通过cgo调用C代码
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.5" data-path="../ch13/ch13-05.html">
            
                <a href="../ch13/ch13-05.html">
            
                    
                    几点忠告
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.15" data-path="../appendix/appendix.html">
            
                <a href="../appendix/appendix.html">
            
                    
                    附录
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.15.1" data-path="../appendix/appendix-a-errata.html">
            
                <a href="../appendix/appendix-a-errata.html">
            
                    
                    附录A：原文勘误
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.15.2" data-path="../appendix/appendix-b-author.html">
            
                <a href="../appendix/appendix-b-author.html">
            
                    
                    附录B：作者译者
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.15.3" data-path="../appendix/appendix-c-cpoyright.html">
            
                <a href="../appendix/appendix-c-cpoyright.html">
            
                    
                    附录C：译文授权
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.15.4" data-path="../appendix/appendix-d-translations.html">
            
                <a href="../appendix/appendix-d-translations.html">
            
                    
                    附录D：其它语言
            
                </a>
            

            
        </li>
    

            </ul>
            
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                                <h2 id="713-&#x7C7B;&#x578B;&#x5206;&#x652F;">7.13. &#x7C7B;&#x578B;&#x5206;&#x652F;</h2>
<p>&#x63A5;&#x53E3;&#x88AB;&#x4EE5;&#x4E24;&#x79CD;&#x4E0D;&#x540C;&#x7684;&#x65B9;&#x5F0F;&#x4F7F;&#x7528;&#x3002;&#x5728;&#x7B2C;&#x4E00;&#x4E2A;&#x65B9;&#x5F0F;&#x4E2D;&#xFF0C;&#x4EE5;io.Reader&#xFF0C;io.Writer&#xFF0C;fmt.Stringer&#xFF0C;sort.Interface&#xFF0C;http.Handler&#x548C;error&#x4E3A;&#x5178;&#x578B;&#xFF0C;&#x4E00;&#x4E2A;&#x63A5;&#x53E3;&#x7684;&#x65B9;&#x6CD5;&#x8868;&#x8FBE;&#x4E86;&#x5B9E;&#x73B0;&#x8FD9;&#x4E2A;&#x63A5;&#x53E3;&#x7684;&#x5177;&#x4F53;&#x7C7B;&#x578B;&#x95F4;&#x7684;&#x76F8;&#x4F3C;&#x6027;&#xFF0C;&#x4F46;&#x662F;&#x9690;&#x85CF;&#x4E86;&#x4EE3;&#x7801;&#x7684;&#x7EC6;&#x8282;&#x548C;&#x8FD9;&#x4E9B;&#x5177;&#x4F53;&#x7C7B;&#x578B;&#x672C;&#x8EAB;&#x7684;&#x64CD;&#x4F5C;&#x3002;&#x91CD;&#x70B9;&#x5728;&#x4E8E;&#x65B9;&#x6CD5;&#x4E0A;&#xFF0C;&#x800C;&#x4E0D;&#x662F;&#x5177;&#x4F53;&#x7684;&#x7C7B;&#x578B;&#x4E0A;&#x3002;</p>
<p>&#x7B2C;&#x4E8C;&#x4E2A;&#x65B9;&#x5F0F;&#x662F;&#x5229;&#x7528;&#x4E00;&#x4E2A;&#x63A5;&#x53E3;&#x503C;&#x53EF;&#x4EE5;&#x6301;&#x6709;&#x5404;&#x79CD;&#x5177;&#x4F53;&#x7C7B;&#x578B;&#x503C;&#x7684;&#x80FD;&#x529B;&#xFF0C;&#x5C06;&#x8FD9;&#x4E2A;&#x63A5;&#x53E3;&#x8BA4;&#x4E3A;&#x662F;&#x8FD9;&#x4E9B;&#x7C7B;&#x578B;&#x7684;&#x8054;&#x5408;&#x3002;&#x7C7B;&#x578B;&#x65AD;&#x8A00;&#x7528;&#x6765;&#x52A8;&#x6001;&#x5730;&#x533A;&#x522B;&#x8FD9;&#x4E9B;&#x7C7B;&#x578B;&#xFF0C;&#x4F7F;&#x5F97;&#x5BF9;&#x6BCF;&#x4E00;&#x79CD;&#x60C5;&#x51B5;&#x90FD;&#x4E0D;&#x4E00;&#x6837;&#x3002;&#x5728;&#x8FD9;&#x4E2A;&#x65B9;&#x5F0F;&#x4E2D;&#xFF0C;&#x91CD;&#x70B9;&#x5728;&#x4E8E;&#x5177;&#x4F53;&#x7684;&#x7C7B;&#x578B;&#x6EE1;&#x8DB3;&#x8FD9;&#x4E2A;&#x63A5;&#x53E3;&#xFF0C;&#x800C;&#x4E0D;&#x5728;&#x4E8E;&#x63A5;&#x53E3;&#x7684;&#x65B9;&#x6CD5;&#xFF08;&#x5982;&#x679C;&#x5B83;&#x786E;&#x5B9E;&#x6709;&#x4E00;&#x4E9B;&#x7684;&#x8BDD;&#xFF09;&#xFF0C;&#x5E76;&#x4E14;&#x6CA1;&#x6709;&#x4EFB;&#x4F55;&#x7684;&#x4FE1;&#x606F;&#x9690;&#x85CF;&#x3002;&#x6211;&#x4EEC;&#x5C06;&#x4EE5;&#x8FD9;&#x79CD;&#x65B9;&#x5F0F;&#x4F7F;&#x7528;&#x7684;&#x63A5;&#x53E3;&#x63CF;&#x8FF0;&#x4E3A;discriminated unions&#xFF08;&#x53EF;&#x8FA8;&#x8BC6;&#x8054;&#x5408;&#xFF09;&#x3002;</p>
<p>&#x5982;&#x679C;&#x4F60;&#x719F;&#x6089;&#x9762;&#x5411;&#x5BF9;&#x8C61;&#x7F16;&#x7A0B;&#xFF0C;&#x4F60;&#x53EF;&#x80FD;&#x4F1A;&#x5C06;&#x8FD9;&#x4E24;&#x79CD;&#x65B9;&#x5F0F;&#x5F53;&#x4F5C;&#x662F;subtype polymorphism&#xFF08;&#x5B50;&#x7C7B;&#x578B;&#x591A;&#x6001;&#xFF09;&#x548C; ad hoc polymorphism&#xFF08;&#x975E;&#x53C2;&#x6570;&#x591A;&#x6001;&#xFF09;&#xFF0C;&#x4F46;&#x662F;&#x4F60;&#x4E0D;&#x9700;&#x8981;&#x53BB;&#x8BB0;&#x4F4F;&#x8FD9;&#x4E9B;&#x672F;&#x8BED;&#x3002;&#x5BF9;&#x4E8E;&#x672C;&#x7AE0;&#x5269;&#x4E0B;&#x7684;&#x90E8;&#x5206;&#xFF0C;&#x6211;&#x4EEC;&#x5C06;&#x4F1A;&#x5448;&#x73B0;&#x4E00;&#x4E9B;&#x7B2C;&#x4E8C;&#x79CD;&#x65B9;&#x5F0F;&#x7684;&#x4F8B;&#x5B50;&#x3002;</p>
<p>&#x548C;&#x5176;&#x5B83;&#x90A3;&#x4E9B;&#x8BED;&#x8A00;&#x4E00;&#x6837;&#xFF0C;Go&#x8BED;&#x8A00;&#x67E5;&#x8BE2;&#x4E00;&#x4E2A;SQL&#x6570;&#x636E;&#x5E93;&#x7684;API&#x4F1A;&#x5E72;&#x51C0;&#x5730;&#x5C06;&#x67E5;&#x8BE2;&#x4E2D;&#x56FA;&#x5B9A;&#x7684;&#x90E8;&#x5206;&#x548C;&#x53D8;&#x5316;&#x7684;&#x90E8;&#x5206;&#x5206;&#x5F00;&#x3002;&#x4E00;&#x4E2A;&#x8C03;&#x7528;&#x7684;&#x4F8B;&#x5B50;&#x53EF;&#x80FD;&#x770B;&#x8D77;&#x6765;&#x50CF;&#x8FD9;&#x6837;&#xFF1A;</p>
<pre><code class="lang-go"><span class="hljs-keyword">import</span> <span class="hljs-string">&quot;database/sql&quot;</span>

<span class="hljs-keyword">func</span> listTracks(db sql.DB, artist <span class="hljs-keyword">string</span>, minYear, maxYear <span class="hljs-keyword">int</span>) {
    result, err := db.Exec(
        <span class="hljs-string">&quot;SELECT * FROM tracks WHERE artist = ? AND ? &lt;= year AND year &lt;= ?&quot;</span>,
        artist, minYear, maxYear)
    <span class="hljs-comment">// ...</span>
}
</code></pre>
<p>Exec&#x65B9;&#x6CD5;&#x4F7F;&#x7528;SQL&#x5B57;&#x9762;&#x91CF;&#x66FF;&#x6362;&#x5728;&#x67E5;&#x8BE2;&#x5B57;&#x7B26;&#x4E32;&#x4E2D;&#x7684;&#x6BCF;&#x4E2A;&apos;?&apos;&#xFF1B;SQL&#x5B57;&#x9762;&#x91CF;&#x8868;&#x793A;&#x76F8;&#x5E94;&#x53C2;&#x6570;&#x7684;&#x503C;&#xFF0C;&#x5B83;&#x6709;&#x53EF;&#x80FD;&#x662F;&#x4E00;&#x4E2A;&#x5E03;&#x5C14;&#x503C;&#xFF0C;&#x4E00;&#x4E2A;&#x6570;&#x5B57;&#xFF0C;&#x4E00;&#x4E2A;&#x5B57;&#x7B26;&#x4E32;&#xFF0C;&#x6216;&#x8005;nil&#x7A7A;&#x503C;&#x3002;&#x7528;&#x8FD9;&#x79CD;&#x65B9;&#x5F0F;&#x6784;&#x9020;&#x67E5;&#x8BE2;&#x53EF;&#x4EE5;&#x5E2E;&#x52A9;&#x907F;&#x514D;SQL&#x6CE8;&#x5165;&#x653B;&#x51FB;&#xFF1B;&#x8FD9;&#x79CD;&#x653B;&#x51FB;&#x5C31;&#x662F;&#x5BF9;&#x624B;&#x53EF;&#x4EE5;&#x901A;&#x8FC7;&#x5229;&#x7528;&#x8F93;&#x5165;&#x5185;&#x5BB9;&#x4E2D;&#x4E0D;&#x6B63;&#x786E;&#x7684;&#x5F15;&#x53F7;&#x6765;&#x63A7;&#x5236;&#x67E5;&#x8BE2;&#x8BED;&#x53E5;&#x3002;&#x5728;Exec&#x51FD;&#x6570;&#x5185;&#x90E8;&#xFF0C;&#x6211;&#x4EEC;&#x53EF;&#x80FD;&#x4F1A;&#x627E;&#x5230;&#x50CF;&#x4E0B;&#x9762;&#x8FD9;&#x6837;&#x7684;&#x4E00;&#x4E2A;&#x51FD;&#x6570;&#xFF0C;&#x5B83;&#x4F1A;&#x5C06;&#x6BCF;&#x4E00;&#x4E2A;&#x53C2;&#x6570;&#x503C;&#x8F6C;&#x6362;&#x6210;&#x5B83;&#x7684;SQL&#x5B57;&#x9762;&#x91CF;&#x7B26;&#x53F7;&#x3002;</p>
<pre><code class="lang-go"><span class="hljs-keyword">func</span> sqlQuote(x <span class="hljs-keyword">interface</span>{}) <span class="hljs-keyword">string</span> {
    <span class="hljs-keyword">if</span> x == <span class="hljs-literal">nil</span> {
        <span class="hljs-keyword">return</span> <span class="hljs-string">&quot;NULL&quot;</span>
    } <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> _, ok := x.(<span class="hljs-keyword">int</span>); ok {
        <span class="hljs-keyword">return</span> fmt.Sprintf(<span class="hljs-string">&quot;%d&quot;</span>, x)
    } <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> _, ok := x.(<span class="hljs-keyword">uint</span>); ok {
        <span class="hljs-keyword">return</span> fmt.Sprintf(<span class="hljs-string">&quot;%d&quot;</span>, x)
    } <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> b, ok := x.(<span class="hljs-keyword">bool</span>); ok {
        <span class="hljs-keyword">if</span> b {
            <span class="hljs-keyword">return</span> <span class="hljs-string">&quot;TRUE&quot;</span>
        }
        <span class="hljs-keyword">return</span> <span class="hljs-string">&quot;FALSE&quot;</span>
    } <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> s, ok := x.(<span class="hljs-keyword">string</span>); ok {
        <span class="hljs-keyword">return</span> sqlQuoteString(s) <span class="hljs-comment">// (not shown)</span>
    } <span class="hljs-keyword">else</span> {
        <span class="hljs-built_in">panic</span>(fmt.Sprintf(<span class="hljs-string">&quot;unexpected type %T: %v&quot;</span>, x, x))
    }
}
</code></pre>
<p>switch&#x8BED;&#x53E5;&#x53EF;&#x4EE5;&#x7B80;&#x5316;if-else&#x94FE;&#xFF0C;&#x5982;&#x679C;&#x8FD9;&#x4E2A;if-else&#x94FE;&#x5BF9;&#x4E00;&#x8FDE;&#x4E32;&#x503C;&#x505A;&#x76F8;&#x7B49;&#x6D4B;&#x8BD5;&#x3002;&#x4E00;&#x4E2A;&#x76F8;&#x4F3C;&#x7684;type switch&#xFF08;&#x7C7B;&#x578B;&#x5206;&#x652F;&#xFF09;&#x53EF;&#x4EE5;&#x7B80;&#x5316;&#x7C7B;&#x578B;&#x65AD;&#x8A00;&#x7684;if-else&#x94FE;&#x3002;</p>
<p>&#x5728;&#x6700;&#x7B80;&#x5355;&#x7684;&#x5F62;&#x5F0F;&#x4E2D;&#xFF0C;&#x4E00;&#x4E2A;&#x7C7B;&#x578B;&#x5206;&#x652F;&#x50CF;&#x666E;&#x901A;&#x7684;switch&#x8BED;&#x53E5;&#x4E00;&#x6837;&#xFF0C;&#x5B83;&#x7684;&#x8FD0;&#x7B97;&#x5BF9;&#x8C61;&#x662F;x.(type)&#x2014;&#x2014;&#x5B83;&#x4F7F;&#x7528;&#x4E86;&#x5173;&#x952E;&#x8BCD;&#x5B57;&#x9762;&#x91CF;type&#x2014;&#x2014;&#x5E76;&#x4E14;&#x6BCF;&#x4E2A;case&#x6709;&#x4E00;&#x5230;&#x591A;&#x4E2A;&#x7C7B;&#x578B;&#x3002;&#x4E00;&#x4E2A;&#x7C7B;&#x578B;&#x5206;&#x652F;&#x57FA;&#x4E8E;&#x8FD9;&#x4E2A;&#x63A5;&#x53E3;&#x503C;&#x7684;&#x52A8;&#x6001;&#x7C7B;&#x578B;&#x4F7F;&#x4E00;&#x4E2A;&#x591A;&#x8DEF;&#x5206;&#x652F;&#x6709;&#x6548;&#x3002;&#x8FD9;&#x4E2A;nil&#x7684;case&#x548C;if x == nil&#x5339;&#x914D;&#xFF0C;&#x5E76;&#x4E14;&#x8FD9;&#x4E2A;default&#x7684;case&#x548C;&#x5982;&#x679C;&#x5176;&#x5B83;case&#x90FD;&#x4E0D;&#x5339;&#x914D;&#x7684;&#x60C5;&#x51B5;&#x5339;&#x914D;&#x3002;&#x4E00;&#x4E2A;&#x5BF9;sqlQuote&#x7684;&#x7C7B;&#x578B;&#x5206;&#x652F;&#x53EF;&#x80FD;&#x4F1A;&#x6709;&#x8FD9;&#x4E9B;case&#xFF1A;</p>
<pre><code class="lang-go"><span class="hljs-keyword">switch</span> x.(<span class="hljs-keyword">type</span>) {
<span class="hljs-keyword">case</span> <span class="hljs-literal">nil</span>:       <span class="hljs-comment">// ...</span>
<span class="hljs-keyword">case</span> <span class="hljs-keyword">int</span>, <span class="hljs-keyword">uint</span>: <span class="hljs-comment">// ...</span>
<span class="hljs-keyword">case</span> <span class="hljs-keyword">bool</span>:      <span class="hljs-comment">// ...</span>
<span class="hljs-keyword">case</span> <span class="hljs-keyword">string</span>:    <span class="hljs-comment">// ...</span>
<span class="hljs-keyword">default</span>:        <span class="hljs-comment">// ...</span>
}
</code></pre>
<p>&#x548C;&#xFF08;&#xA7;1.8&#xFF09;&#x4E2D;&#x7684;&#x666E;&#x901A;switch&#x8BED;&#x53E5;&#x4E00;&#x6837;&#xFF0C;&#x6BCF;&#x4E00;&#x4E2A;case&#x4F1A;&#x88AB;&#x987A;&#x5E8F;&#x7684;&#x8FDB;&#x884C;&#x8003;&#x8651;&#xFF0C;&#x5E76;&#x4E14;&#x5F53;&#x4E00;&#x4E2A;&#x5339;&#x914D;&#x627E;&#x5230;&#x65F6;&#xFF0C;&#x8FD9;&#x4E2A;case&#x4E2D;&#x7684;&#x5185;&#x5BB9;&#x4F1A;&#x88AB;&#x6267;&#x884C;&#x3002;&#x5F53;&#x4E00;&#x4E2A;&#x6216;&#x591A;&#x4E2A;case&#x7C7B;&#x578B;&#x662F;&#x63A5;&#x53E3;&#x65F6;&#xFF0C;case&#x7684;&#x987A;&#x5E8F;&#x5C31;&#x4F1A;&#x53D8;&#x5F97;&#x5F88;&#x91CD;&#x8981;&#xFF0C;&#x56E0;&#x4E3A;&#x53EF;&#x80FD;&#x4F1A;&#x6709;&#x4E24;&#x4E2A;case&#x540C;&#x65F6;&#x5339;&#x914D;&#x7684;&#x60C5;&#x51B5;&#x3002;default case&#x76F8;&#x5BF9;&#x5176;&#x5B83;case&#x7684;&#x4F4D;&#x7F6E;&#x662F;&#x65E0;&#x6240;&#x8C13;&#x7684;&#x3002;&#x5B83;&#x4E0D;&#x4F1A;&#x5141;&#x8BB8;&#x843D;&#x7A7A;&#x53D1;&#x751F;&#x3002;</p>
<p>&#x6CE8;&#x610F;&#x5230;&#x5728;&#x539F;&#x6765;&#x7684;&#x51FD;&#x6570;&#x4E2D;&#xFF0C;&#x5BF9;&#x4E8E;bool&#x548C;string&#x60C5;&#x51B5;&#x7684;&#x903B;&#x8F91;&#x9700;&#x8981;&#x901A;&#x8FC7;&#x7C7B;&#x578B;&#x65AD;&#x8A00;&#x8BBF;&#x95EE;&#x63D0;&#x53D6;&#x7684;&#x503C;&#x3002;&#x56E0;&#x4E3A;&#x8FD9;&#x4E2A;&#x505A;&#x6CD5;&#x5F88;&#x5178;&#x578B;&#xFF0C;&#x7C7B;&#x578B;&#x5206;&#x652F;&#x8BED;&#x53E5;&#x6709;&#x4E00;&#x4E2A;&#x6269;&#x5C55;&#x7684;&#x5F62;&#x5F0F;&#xFF0C;&#x5B83;&#x53EF;&#x4EE5;&#x5C06;&#x63D0;&#x53D6;&#x7684;&#x503C;&#x7ED1;&#x5B9A;&#x5230;&#x4E00;&#x4E2A;&#x5728;&#x6BCF;&#x4E2A;case&#x8303;&#x56F4;&#x5185;&#x90FD;&#x6709;&#x6548;&#x7684;&#x65B0;&#x53D8;&#x91CF;&#x3002;</p>
<pre><code class="lang-go"><span class="hljs-keyword">switch</span> x := x.(<span class="hljs-keyword">type</span>) { <span class="hljs-comment">/* ... */</span> }
</code></pre>
<p>&#x8FD9;&#x91CC;&#x6211;&#x4EEC;&#x5DF2;&#x7ECF;&#x5C06;&#x65B0;&#x7684;&#x53D8;&#x91CF;&#x4E5F;&#x547D;&#x540D;&#x4E3A;x&#xFF1B;&#x548C;&#x7C7B;&#x578B;&#x65AD;&#x8A00;&#x4E00;&#x6837;&#xFF0C;&#x91CD;&#x7528;&#x53D8;&#x91CF;&#x540D;&#x662F;&#x5F88;&#x5E38;&#x89C1;&#x7684;&#x3002;&#x548C;&#x4E00;&#x4E2A;switch&#x8BED;&#x53E5;&#x76F8;&#x4F3C;&#x5730;&#xFF0C;&#x4E00;&#x4E2A;&#x7C7B;&#x578B;&#x5206;&#x652F;&#x9690;&#x5F0F;&#x7684;&#x521B;&#x5EFA;&#x4E86;&#x4E00;&#x4E2A;&#x8BCD;&#x6CD5;&#x5757;&#xFF0C;&#x56E0;&#x6B64;&#x65B0;&#x53D8;&#x91CF;x&#x7684;&#x5B9A;&#x4E49;&#x4E0D;&#x4F1A;&#x548C;&#x5916;&#x9762;&#x5757;&#x4E2D;&#x7684;x&#x53D8;&#x91CF;&#x51B2;&#x7A81;&#x3002;&#x6BCF;&#x4E00;&#x4E2A;case&#x4E5F;&#x4F1A;&#x9690;&#x5F0F;&#x7684;&#x521B;&#x5EFA;&#x4E00;&#x4E2A;&#x5355;&#x72EC;&#x7684;&#x8BCD;&#x6CD5;&#x5757;&#x3002;</p>
<p>&#x4F7F;&#x7528;&#x7C7B;&#x578B;&#x5206;&#x652F;&#x7684;&#x6269;&#x5C55;&#x5F62;&#x5F0F;&#x6765;&#x91CD;&#x5199;sqlQuote&#x51FD;&#x6570;&#x4F1A;&#x8BA9;&#x8FD9;&#x4E2A;&#x51FD;&#x6570;&#x66F4;&#x52A0;&#x7684;&#x6E05;&#x6670;&#xFF1A;</p>
<pre><code class="lang-go"><span class="hljs-keyword">func</span> sqlQuote(x <span class="hljs-keyword">interface</span>{}) <span class="hljs-keyword">string</span> {
    <span class="hljs-keyword">switch</span> x := x.(<span class="hljs-keyword">type</span>) {
    <span class="hljs-keyword">case</span> <span class="hljs-literal">nil</span>:
        <span class="hljs-keyword">return</span> <span class="hljs-string">&quot;NULL&quot;</span>
    <span class="hljs-keyword">case</span> <span class="hljs-keyword">int</span>, <span class="hljs-keyword">uint</span>:
        <span class="hljs-keyword">return</span> fmt.Sprintf(<span class="hljs-string">&quot;%d&quot;</span>, x) <span class="hljs-comment">// x has type interface{} here.</span>
    <span class="hljs-keyword">case</span> <span class="hljs-keyword">bool</span>:
        <span class="hljs-keyword">if</span> x {
            <span class="hljs-keyword">return</span> <span class="hljs-string">&quot;TRUE&quot;</span>
        }
        <span class="hljs-keyword">return</span> <span class="hljs-string">&quot;FALSE&quot;</span>
    <span class="hljs-keyword">case</span> <span class="hljs-keyword">string</span>:
        <span class="hljs-keyword">return</span> sqlQuoteString(x) <span class="hljs-comment">// (not shown)</span>
    <span class="hljs-keyword">default</span>:
        <span class="hljs-built_in">panic</span>(fmt.Sprintf(<span class="hljs-string">&quot;unexpected type %T: %v&quot;</span>, x, x))
    }
}
</code></pre>
<p>&#x5728;&#x8FD9;&#x4E2A;&#x7248;&#x672C;&#x7684;&#x51FD;&#x6570;&#x4E2D;&#xFF0C;&#x5728;&#x6BCF;&#x4E2A;&#x5355;&#x4E00;&#x7C7B;&#x578B;&#x7684;case&#x5185;&#x90E8;&#xFF0C;&#x53D8;&#x91CF;x&#x548C;&#x8FD9;&#x4E2A;case&#x7684;&#x7C7B;&#x578B;&#x76F8;&#x540C;&#x3002;&#x4F8B;&#x5982;&#xFF0C;&#x53D8;&#x91CF;x&#x5728;bool&#x7684;case&#x4E2D;&#x662F;bool&#x7C7B;&#x578B;&#x548C;string&#x7684;case&#x4E2D;&#x662F;string&#x7C7B;&#x578B;&#x3002;&#x5728;&#x6240;&#x6709;&#x5176;&#x5B83;&#x7684;&#x60C5;&#x51B5;&#x4E2D;&#xFF0C;&#x53D8;&#x91CF;x&#x662F;switch&#x8FD0;&#x7B97;&#x5BF9;&#x8C61;&#x7684;&#x7C7B;&#x578B;&#xFF08;&#x63A5;&#x53E3;&#xFF09;&#xFF1B;&#x5728;&#x8FD9;&#x4E2A;&#x4F8B;&#x5B50;&#x4E2D;&#x8FD0;&#x7B97;&#x5BF9;&#x8C61;&#x662F;&#x4E00;&#x4E2A;interface{}&#x3002;&#x5F53;&#x591A;&#x4E2A;case&#x9700;&#x8981;&#x76F8;&#x540C;&#x7684;&#x64CD;&#x4F5C;&#x65F6;&#xFF0C;&#x6BD4;&#x5982;int&#x548C;uint&#x7684;&#x60C5;&#x51B5;&#xFF0C;&#x7C7B;&#x578B;&#x5206;&#x652F;&#x53EF;&#x4EE5;&#x5F88;&#x5BB9;&#x6613;&#x7684;&#x5408;&#x5E76;&#x8FD9;&#x4E9B;&#x60C5;&#x51B5;&#x3002;</p>
<p>&#x5C3D;&#x7BA1;sqlQuote&#x63A5;&#x53D7;&#x4E00;&#x4E2A;&#x4EFB;&#x610F;&#x7C7B;&#x578B;&#x7684;&#x53C2;&#x6570;&#xFF0C;&#x4F46;&#x662F;&#x8FD9;&#x4E2A;&#x51FD;&#x6570;&#x53EA;&#x4F1A;&#x5728;&#x5B83;&#x7684;&#x53C2;&#x6570;&#x5339;&#x914D;&#x7C7B;&#x578B;&#x5206;&#x652F;&#x4E2D;&#x7684;&#x4E00;&#x4E2A;case&#x65F6;&#x8FD0;&#x884C;&#x5230;&#x7ED3;&#x675F;&#xFF1B;&#x5176;&#x5B83;&#x60C5;&#x51B5;&#x7684;&#x5B83;&#x4F1A;panic&#x51FA;&#x201C;unexpected type&#x201D;&#x6D88;&#x606F;&#x3002;&#x867D;&#x7136;x&#x7684;&#x7C7B;&#x578B;&#x662F;interface{}&#xFF0C;&#x4F46;&#x662F;&#x6211;&#x4EEC;&#x628A;&#x5B83;&#x8BA4;&#x4E3A;&#x662F;&#x4E00;&#x4E2A;int&#xFF0C;uint&#xFF0C;bool&#xFF0C;string&#xFF0C;&#x548C;nil&#x503C;&#x7684;discriminated union&#xFF08;&#x53EF;&#x8BC6;&#x522B;&#x8054;&#x5408;&#xFF09;</p>

                                
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